Question
A molten mixture of aluminium oxide and cryolite is electrolysed to manufacture aluminium. At which electrode does the aluminium form?
Answer
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Penelope
Master · Tutor for 5 years
Answer
Aluminum forms at the cathode (negative electrode).
Explanation
During electrolysis, the Al^3+ ions are attracted to a specific electrode depending on the charge. Al^3+ are positive ions. They are attracted to the electrode with the opposite charge because like charges repel each other and opposite charges attract each other. Therefore, the Al^3+ ions move towards the negative electrode, also known as the cathode. At the cathode, the Al^3+ ions gain electrons (which are negatively charged particles that reside in the electrode). This process is called reduction. Through reduction, the Al^3+ ions are transformed into neutral Al atoms. These Al atoms immediately coagulate to form aluminum metal. Since aluminum forms at the electrode where reduction takes place (the negative electrode), we can conclude that: